Also AMD seemly releases some "Pro" features for workstation on Linux first.
The problem of Linux gaming is not the graphics drivers, in fact this part has been working "ok" for a while now.
The problem with Linux gaming is:
1. Audio is still a mess, the fastest audio library still is OSS4 (not 3), that won't ever get in the mainstream distributions (sometimes it is even explicitly banned and will get you banned from forums and irc servers if you ask about it), JACK still is finnicky to work with, PA is still buggy and slow, and ALSA although much better now, is also too slow and has terrible API (while coding for OSS, any version, is very easy).
2. Desktop is still a pain to setup, even the most "GUI-happy" distros still have problems here and there, when I asked some random people about it, I got outright hostile replies, people telling me they deliberately don't want to make Linux easier, because they don't want "dumb people using something they are not worth using", mind you, this wasn't once, or in one community, more than one person shared this view with me.
3. Some people in the community are outright hostile to games, and even sabotage efforts to make games work better, I saw a flamewar where one guy was claiming games were purely dumb entertainment, and that people that played games weren't not only inferior humans, but people that deserved Windows, as punishment. This guy was of the opinion that no GUI server should ever support exclusive fullscreen properly, that instead they should have all features focused on "Work" features always.
4. Lots of other random hardware is a pain to setup on Linux, even things that usually don't cross people minds, for example I couldn't figure how to make Linux properly support my motherboard Super I/O chip, that is even a common one, I even convinced the manufacturer to give me the chip datasheet, but I couldn't even figure to what project I would need to contribute code. (as for what the Super I/O chip does: control the motherboard sensors, fans and power distribution, including voltage values and regulation commands on my motherboard)